Generally, while user does not use the cordless hand-held apparatus, the cordless electric-apparatus still consumes power as normal, such consumption is unnecessary. It shortens battery working time, and the user must replace battery frequently.
Thereafter, typical examples for minimizing the power consumption are disclosed. A cordless electric-apparatus utilizes a device having a timer to decrease power consumption. When user stop working, the timer starts timing till a predetermine time expired, the device will change cordless hand-held apparatus working state to a sleep mode in order to decrease power consumption. When the device detects actions that the apparatus was used again like apparatus moved or keys pressed, the device will transmit signal to wake up the apparatus for working as normal. Such device can decrease the power consumption, however, the cordless hand-held apparatus will consume electrical power until the apparatus switching to power saving state or sleep mode.
Other typical examples for minimizing the power consumption is disclosed. A cordless electric-apparatus has a light source emitting a light beam and a detector receiving light beam reflected from user body. Therefore, the apparatus will know whether user is using cordless hand-held apparatus or not. According to the judgment, the apparatus working state was switched to power saving mode. However, disadvantage of the design is that the light source will consume electrical power, and such invention can not judge whether the shield is body or not, that is, when other objects shield the light beam, the cordless hand-held apparatus will be activated.